Walking assistance method and apparatuses

ABSTRACT

A walking assistance method may include measuring a current gait motion of a user, defining a state variable based on the current gait motion, setting a delay that is a feedback element for the state variable, and generating a torque profile based on the state variable and the delay.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/861,832 filed Jan. 4, 2018, and which claims benefit under 35 U.S.C.§ 119 to Korean Patent Application No. 10-2017-0075634, filed on Jun.15, 2017, in the Korean Intellectual Property Office, the entirecontents of which are incorporated herein by reference in its entirety.

BACKGROUND 1. Field

At least one example embodiment relates to a walking assistance methodand/or an apparatuses configured to perform same.

2. Description of the Related Art

With the onset of rapidly aging societies, an increased number of peoplewho experience inconvenience and agony from joint problems isincreasing, and accordingly an interest in motion assistance apparatusesthat may enable the elderly or patients having joint problems to walkwith less effort is growing. Also, motion assistance apparatuses toincrease a muscular strength of a human body are being developed, forexample, for military purposes.

For example, a motion assistance apparatus may include a body framedisposed on a trunk of a user, a pelvic frame coupled to a lower side ofthe body frame to cover a pelvis of the user, a femoral frame disposedon a thigh of the user, a sural frame disposed on a calf of the user,and a pedial frame disposed on a foot of the user. The pelvic frame andthe femoral frame may be connected rotatably by a hip joint portion, andthe femoral frame and the sural frame may be connected rotatably by aknee joint portion. Also, the sural frame and the pedial frame may beconnected rotatably by an ankle joint portion.

The motion assistance apparatus may be controlled based on feed-forwardbased torque patterns at predicted gait phases, which may work well insteady state, but may cause problems in scenarios when it is difficultto predict the gait phases (e.g., when a user has a discontinuous orirregular gait pattern).

SUMMARY

Some example embodiments relate to a walking assistance method.

In some example embodiments, the walking assistance method includesmeasuring a current gait motion of a user; defining a state variablebased on the current gait motion; setting a delay associated with thestate variable; and generating a torque profile based on the statevariable and the delay such that the delay is a feedback elementdefining an output time of torque corresponding to the torque profile.

In some example embodiments, the walking assistance method furtherincludes filtering the current gait motion.

In some example embodiments, the filtering of the current gait motionincludes performing low-pass filtering of the current gait motion usinga low-pass filter (LPF).

In some example embodiments, the measuring of the current gait motionincludes measuring at least one hip joint angle of the user.

In some example embodiments, the measuring of the at least one hip jointangle includes measuring a left hip joint angle of the user; andmeasuring a right hip joint angle of the user.

In some example embodiments, the defining of the state variable includesdefining the state variable based on a difference between the left hipjoint angle and the right hip joint angle.

In some example embodiments, the defining of the state variable definesthe state variable such that the state variable is expressed in a formof a trigonometric function.

In some example embodiments, the defining of the state variable includesexpressing a left hip joint angle of the user based on a firsttrigonometric function; expressing a right hip joint angle of the userbased on a second trigonometric function; and defining the statevariable based on a difference between the first trigonometric functionand the second trigonometric function.

In some example embodiments, the state variable includes the delay and again associated with the torque.

In some example embodiments, the defining of the state variable includesdetermining the delay based on a gait velocity of the user.

Some example embodiments relate to a walking assistance apparatus.

In some example embodiments, the walking assistance apparatus includes asensor configured to measure a current gait motion of a user; and acontroller configured to, define a state variable based on the currentgait motion, set a delay for the state variable, and generate a torqueprofile based on the state variable and the delay such that the delay isa feedback element defining an output timing of a torque correspondingto the torque profile.

In some example embodiments, the walking assistance apparatus furtherincludes a filter configured to filter the current gait motion.

In some example embodiments, the filter includes a low-pass filter (LPF)configured to perform low-pass filtering on the current gait motion.

In some example embodiments, the sensor is configured to measure a hipjoint angle of the user as the current gait motion.

In some example embodiments, the sensor is configured to, measure a lefthip joint angle of the user, and measure a right hip joint angle of theuser.

In some example embodiments, the controller is configured to define thestate variable based on a difference between the left hip joint angleand the right hip joint angle.

In some example embodiments, the controller is configured to define thestate variable such that the state variable is expressed in a form of atrigonometric function.

In some example embodiments, the controller is configured to define thestate variable by, expressing a left hip joint angle of the user basedon a first trigonometric function, expressing a right hip joint angle ofthe user based on a second trigonometric function, and defining thestate variable based on a difference between the first trigonometricfunction and the second trigonometric function.

In some example embodiments, the state variable includes the delay and again associated with the torque.

In some example embodiments, the controller is configured to determinethe delay based on a gait velocity of the user.

Additional aspects of example embodiments will be set forth in part inthe description which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of example embodiments, takenin conjunction with the accompanying drawings of which:

FIG. 1 is a block diagram illustrating a walking assistance apparatusaccording to at least one example embodiment;

FIG. 2 is a diagram illustrating an operation of the walking assistanceapparatus of FIG. 1;

FIG. 3 is a front view illustrating the walking assistance apparatus ofFIG. 1 worn on an object;

FIG. 4 is a side view illustrating the walking assistance apparatus ofFIG. 1 worn on the object;

FIG. 5A is a diagram illustrating an example of an operation of a sensorand a controller of FIG. 1;

FIG. 5B is a diagram illustrating another example of an operation of thesensor and the controller of FIG. 1;

FIG. 6A is a diagram illustrating an example for evaluation of aperformance of the walking assistance apparatus of FIG. 1;

FIG. 6B is a diagram illustrating another example for evaluation of theperformance of the walking assistance apparatus of FIG. 1;

FIGS. 7A and 7B are a three-dimensional (3D) graph and a two-dimensional(2D) graph illustrating a result obtained by evaluating the performanceof the walking assistance apparatus of FIG. 1, respectively;

FIG. 8A is a diagram illustrating an example of a stability analysis mapassociated with the result of FIGS. 7A and 7B;

FIG. 8B is a diagram illustrating another example of a stabilityanalysis map associated with the result of FIGS. 7A and 7B;

FIG. 9A is a graph illustrating a result of an experiment on a change ina gait velocity of a user according to at least one example embodiment;

FIG. 9B is a diagram illustrating a stability analysis map associatedwith the result of FIG. 9A;

FIG. 10 illustrates experimental results when a user repeats walking andstopping according to at least one example embodiment;

FIG. 11 illustrates experimental results when a user who is stationarywants to walk according to at least one example embodiment;

FIG. 12 illustrates experimental results when a user wants to walkuphill and then downhill according to at least one example embodiment;

FIG. 13 is a flowchart illustrating a walking assistance methodperformed by the walking assistance apparatus 100 of FIG. 1 according toat least one example embodiment;

FIG. 14 is a flowchart illustrating an operation of measuring a currentgait motion of a user in the walking assistance method of FIG. 13;

FIG. 15 is a flowchart illustrating an example of an operation ofdefining a state variable in the walking assistance method of FIG. 13;

FIG. 16 is a flowchart illustrating another example of an operation ofdefining a state variable in the walking assistance method of FIG. 13;

FIG. 17 is a block diagram illustrating an example of a walkingassistance system according to at least one example embodiment;

FIG. 18 is a graph illustrating an example of using the walkingassistance apparatus 100 as a phase estimator according to at least oneexample embodiment;

FIG. 19 is a block diagram illustrating another example of a walkingassistance system according to at least one example embodiment;

FIG. 20 is a block diagram illustrating still another example of awalking assistance system according to at least one example embodiment;and

FIG. 21 illustrates a flowchart illustrating method of operating awalking assistance system for tremor control according to at least oneexample embodiment.

DETAILED DESCRIPTION

The following structural or functional descriptions of some exampleembodiments disclosed in the present disclosure are merely intended forthe purpose of describing the example embodiments and the exampleembodiments may be implemented in various forms. The example embodimentsare not meant to be limited, but it is intended that variousmodifications are also covered within the scope of the claims.

Various modifications may be made to the example embodiments. However,it should be understood that these embodiments are not construed aslimited to the illustrated forms and include all changes, equivalents oralternatives within the idea and the technical scope of this disclosure.

Although terms of “first,” “second,” etc. are used to explain variouscomponents, the components are not limited to such terms. These termsare used only to distinguish one component from another component. Forexample, a first component may be referred to as a second component, orsimilarly, the second component may be referred to as the firstcomponent within the scope of the right according to the exampleembodiments of the inventive concepts of the present disclosure.

It should be noted that if it is described in the specification that onecomponent is “connected” or “coupled” to another component, a thirdcomponent may be “connected” or “coupled” between the first and secondcomponents, although the first component may be directly connected orcoupled to the second component. In addition, it should be noted that ifit is described in the specification that one component is “directlyconnected” or “directly coupled” to another component, a third componentmay not be present therebetween. Likewise, expressions, for example,“between” and “immediately between” and “adjacent to” and “immediatelyadjacent to” may also be construed as described in the foregoing

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “include” and/or“have,” when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components orcombinations thereof, but do not preclude the presence or addition ofone or more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms including technical and scientificterms used herein have the same meaning as commonly understood by one ofordinary skill in the art to which these example embodiments belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Regarding the reference numerals assigned to the elements in thedrawings, it should be noted that the same elements will be designatedby the same reference numerals, wherever possible, even though they areshown in different drawings. Also, in the description of embodiments,detailed description of well-known related structures or functions willbe omitted when it is deemed that such description will cause ambiguousinterpretation of the present disclosure.

A user of the walking assistance apparatus may be a patient who has adifficulty in walking normally, that is, who walks abnormally, forexample, a patient who suffers from a stroke, a Charcot-Marie-Tooth(CMT) disease or a Parkinson's disease. A pathological gait or abnormalgait may refer to a gait to preserve an abnormal or pathological gaitpattern through an adaptation of a human body system by sacrificing anormal gait pattern because the normal gait pattern collapses as aresult of a functional disorder due to, for example, a partial injury, aweakness, a loss of flexibility, a pain, a bad habit, and a neural ormuscular injury. The abnormal gait may indicate, for example, apathological gait including at least one of abnormal gait types thatwill be described below.

The abnormal gait types may include, for example, at least one of acrouch gait (or a genu recurvatum gait), a steppage gait (or a footdropgait), an antalgic gait, an ataxic gait, a festinating gait, a vaultinggait, a lurching gait, an equinus gait, a short leg gait, a hemiplegicgait, a circumduction gait, a tabetic gait, a neurogenic gait, ascissoring gait, or a parkinsonian gait.

The crouch gait may refer to walking with a posture in which all hipjoints, knee joints and ankle joints are bent to overcome a gaitinstability. The steppage gait may refer to walking with a posture inwhich toes point downward on the ground and a top of a foot is droppedto the ground. The antalgic gait may refer to waling to lessen a pain ona painful portion. The ataxic gait may refer to walking with an unevenstride, a wide space between feet, a shaken body, and an unstable stepappearing intoxicated. The festinating gait may refer to walking with aposture in which a trunk leans forward with a small stride withoutmoving arms and an increase in a gait velocity as if it is impossible tostop walking. The vaulting gait may refer to walking using a leg of anon-affected side, for example, a non-paralyzed side, instead of a legof an affected side, for example, a paralyzed side, when a knee joint isnot extendable.

The lurching gait may refer to all staggering gaits, and may include,for example, a waddling gait, a gluteus maximus gait, or a Trendelenburggait. The waddling gait may refer to swaying from side to side whilewalking. The gluteus maximus gait may refer to walking with a posture inwhich a chest is bent backward to maintain a hip extension and a wholetrunk is suddenly moved from time to time. The Trendelenburg gait mayrefer to walking with a posture in which a chest tilts toward an injuredleg to maintain a center of gravity and to prevent a pelvis of aninjured side from drooping when standing on the ground with an injuredlower limb.

The equines gait may refer to walking using tiptoes while heels are notin contact with the ground. The hemiplegic gait may refer to walkingwith a posture in which, due to a stiffness, an entire body is slightlytilted to an affected side, a swing of an upper arm in the affected sideis lost and a lower limb appears in a primitively curved form in a statein which a shoulder of the affected side descends. The circumductiongait may refer to walking with a posture in which an entire leg swingsdue to a difficulty in bending a knee. The scissoring gait may refer tocrossing or grazing legs or knees against to one another with asquatting posture in a state in which the legs are slightly bent inward.The Parkinsonian gait may refer to walking as if shuffling a sole on theground with an anterior flexion posture.

FIG. 1 illustrates a walking assistance apparatus 100 according to atleast one example embodiment, and FIG. 2 illustrates an operation of thewalking assistance apparatus 100. FIG. 3 is a front view illustratingthe walking assistance apparatus 100 worn on an object, and FIG. 4 is aside view illustrating the walking assistance apparatus 100 worn on theobject.

Referring to FIGS. 1 through 4, the walking assistance apparatus mayinclude a sensor 110, a controller 120, a driver 130 and a display 140.Also, the walking assistance apparatus 100 may further include a filter(not shown), a force transmitting member 150, a supporting member 160,and a fixing member 170.

The walking assistance apparatus 100 may be worn on an object, forexample, a user 200, to assist a gait and/or a motion of the user 200.The object may be, for example, a human, an animal or a robot, and thereis no limitation thereto.

While FIGS. 3 and 4 illustrate a hip-type walking assistance apparatus,when the walking assistance apparatus 100 is worn on a thigh of the user200, however, a type of the walking assistance apparatus 100 is notlimited thereto. For example, the walking assistance apparatus 100 maybe worn on at least one part of the upper body of the user 200, forexample, a hand, an upper arm or a lower arm, or on at least one part ofthe lower body of the user 200, for example, a foot or a calf, and mayassist a gait and/or motion of the user 200. The walking assistanceapparatus 100 may be applicable to, for example, a walking assistanceapparatus for supporting a portion of a pelvic limb, a walkingassistance apparatus for supporting up to a knee, and a walkingassistance apparatus for supporting up to an ankle, or a walkingassistance apparatus for supporting a whole body.

The walking assistance apparatus 100 may assist a gait and/or a motionof another part of an upper body of the user 200, for example, a hand,an upper arm or a lower arm, or may assist a gait and/or a motion ofanother part of a lower body of the user 200, for example, a foot, acalf or a thigh. Thus, the walking assistance apparatus 100 may assist agait and/or a motion of a part of the user 200.

As discussed in more detail below, the walking assistance apparatus 100may measure a current gait motion of the user 200. When the walkingassistance apparatus 100 measures the current gait motion, an externalforce τ_(ext) due to an interaction between the walking assistanceapparatus 100 and the user 200 may also be measured. The walkingassistance apparatus 100 may define a state variable y based on thecurrent gait motion. The walking assistance apparatus 100 may set adelay Δt for the state variable y. The delay Δt may be a feedbackelement. In some example embodiments, the delay Δt may be a time valueset in advance by a user, and, in other example embodiments, the walkingassistance apparatus 100 may automatically determine the delay Δt. Thewalking assistance apparatus 100 may generate a torque profile based onthe state variable y and the delay Δt. The walking assistance apparatus100 may output an assistance torque based on the torque profile, toassist a gait and/or motion of the user 200.

The walking assistance apparatus 100 may continue to perform anassistance operation by measuring the current gait motion of the user200 assisted by the walking assistance apparatus 100.

The sensor 110 may include a first sensor configured to measure hipjoint angular information associated with a right hip joint, and asecond sensor configured to measure hip joint angular informationassociated with a left hip joint angle. The hip joint angularinformation may include at least one of hip joint angles of the hipjoints, a difference between the hip joint angles, directions of motionsfor the hip joints, or angular velocity information for the hip joints.

The sensor 110 may be implemented as, for example, a hall sensor. Inother example embodiments, the sensor 110 may include a potentiometerthat senses an R-axis joint angle and an L-axis joint angle, and anR-axis joint angular velocity and an L-axis joint angular velocity basedon a walking motion of the user.

As shown in FIG. 4, the sensor 110 may be implemented in at least one ofthe driver 130, the force transmitting member 150 or the supportingmember 160.

The sensor 110 may transmit the hip joint angular information to thecontroller 120 via a wire or wirelessly.

The filter (not shown) may perform filtering of the hip joint angularinformation representing the current gait motion. The filter may beimplemented as, for example, a low-pass filter (LPF). The filter mayperform low-pass filtering of the hip joint angular information toremove noise from the hip joint angular information. The noise presentin the hip joint angular information may be, for example, user movementand/or ground contact external shock.

The controller 120 may include processing circuitry (not shown) and thememory 125.

The processing circuitry may be, but not limited to, a processor,Central Processing Unit (CPU), a controller, an arithmetic logic unit(ALU), a digital signal processor, a microcomputer, a field programmablegate array (FPGA), an Application Specific Integrated Circuit (ASIC), aSystem-on-Chip (SoC), a programmable logic unit, a microprocessor, orany other device capable of performing operations in a defined manner.

The processing circuitry may be configured, through a layout design orexecution of computer readable instructions stored in the memory, as aspecial purpose computer to perform the operations illustrated in FIG.13 and the sub-operations thereof, discussed below.

The controller 120 may control an overall operation of the walkingassistance apparatus 100. For example, the controller 120 may controlthe driver 130 to output a force to assist a gait of the user 200. Theforce may refer to a force used to extend or flex legs of the user 200.Also, the force may be, for example, an assistance torque.

The controller 120 may define a state variable based on the current gaitmotion received from the sensor 110. For example, the controller 120 mayreceive the current gait motion as feedback from the sensor 110, and maydefine the state variable. Also, the controller 120 may generate atorque profile based on the state variable.

The controller 120 may control the driver 130 to start to assist a gaitof the user 200 based on the torque profile. The controller 120 mayinitiate an output of the torque profile to assist the gait of the user200. Also, the controller 120 may control the driver 130 to terminateassistance of the gait. The controller 120 may terminate the output ofthe torque profile.

The controller 120 may control an assistance torque output by the driver130 to the user based on the torque profile. The controller 120 maycontrol an assistance torque that is output immediately in response to acurrent motion of the user 200, to prevent a mismatch between the user200 and the walking assistance apparatus 100 in advance by flexiblycoping with a sudden change in a motion of the user 200. Thus, thecontroller 120 may output a high assistance torque to the user 200 toactively assist a gait of the user 200.

The controller 120 may set a gain associated with a torque strength anda delay associated with a torque output time, and may define a statevariable. For example, the controller 120 may control a strength of anassistance torque applied to the user 200 based on the gain, and maycontrol a time at which the assistance torque is to be output based onthe delay. In this example, the controller 120 may stably respond to achange in a surrounding environment or a sudden motion of the user 200and stop of the motion, and may enhance a regularity and stability sothat the user 200 may periodically walk.

The memory 125 be implemented as a volatile memory or a non-volatilememory. Examples of the volatile memory include, but are not limited to,RAM (random access memory), SRAM (static RAM), DRAM (dynamic RAM), SDRAM(synchronous DRAM), T-RAM (thyristor RAM), Z-RAM (zero capacitor RAM),or TTRAM (Twin Transistor RAM). Examples of the non-volatile memoryinclude, but are not limited to, electrically erasable programmableread-only memory (EEPROM), flash memory, magnetic RAM (MRAM),spin-transfer torque MRAM, ferroelectric RAM (FeRAM), phase change RAM(PRAM), or RRAM (resistive RAM). Further, the nonvolatile memory may beimplemented as a multimedia card (MMC), an embedded MMC (eMMC), auniversal flash storage (UFS), a solid state drive (SSD), a USB flashdrive, or a hard disk drive (HDD).

The memory 125 may store torque parameters corresponding to the torqueprofile output by the controller 120. The controller 120 may analyze agait pattern of a user based on the torque parameters. Also, thecontroller 120 may output a periodic torque to assist a gait based onthe torque parameters.

Although the memory 125 may be included in the controller 120 in FIG. 3,the memory 125 may be located outside the controller 120.

The driver 110 may include one or more motors that generate a rotationaltorque that is applied as a force to assist a gait of the user 200 basedon a control of the controller 120, for example, based on the torqueprofile generated by the controller 120.

The driver 130 may drive both the hip joints of the user 200. The driver130 may be located on, for example, a right hip portion and/or a lefthip portion of the user 200.

The display 140 may be implemented as, for example, a touch screen, aliquid crystal display (LCD), a thin film transistor-liquid crystaldisplay (TFT-LCD), a light emitting diode (LED) display, an organic LED(OLED) display, an active matrix OLED (AMOLED) display, or a flexibledisplay.

The display 140 may display a user interface (UI) configured to controla gain and/or a delay to the user 200. For example, the user 200 maycontrol, using the UI displayed on the display 140, a gain associatedwith a strength of an assistance torque and/or control a delayassociated with a time at which the assistance torque is to be output.

The force transmitting member 150 may include, for example, alongitudinal member such as a frame, a wire, a cable, a string, a rubberband, a spring, a belt, or a chain.

The force transmitting member 150 may connect the driver 130 and thesupporting member 160. The force transmitting member 150 may transmitthe force from the driver 130 to the supporting member 160.

The supporting member 160 may support a target part, for example, athigh of the user 200. The supporting member 160 may be disposed tocover at least a part of the user 200. The supporting member 160 mayapply the force received from the force transmitting member 150 to apart of the user 200 to be supported.

The fixing member 170 may be attached to a part, for example, a waist ofthe user 200. The fixing member 170 may be in contact with at least aportion of an external surface of the user 200. The fixing member 170may have a shape to cover the external surface of the user.

FIG. 5A illustrates an example of an operation of the sensor 110 and thecontroller 120 of FIG. 1, and FIG. 5B illustrates another example of anoperation of the sensor 110 and the controller 120.

Referring to FIGS. 5A and 5B, the sensor 110 may measure the hip jointangular information as the current gait motion of the user 200. Thecurrent gait motion may include a left hip joint angle q_(l) and a righthip joint angle q_(r). The sensor 110 may measure the left hip jointangle q_(l) and the right hip joint angle q_(r) and may transmit theleft hip joint angle q_(l) and the right hip joint angle q_(r) to thecontroller 120.

The controller 120 may define a state variable (y) based on the left hipjoint angle q_(l) and the right hip joint angle q_(r).

In an examplc, the controllcr 120 may definc the state variable (y)based on a difference “q_(r)−q_(l)” between the left hip joint angleq_(l) and the right hip joint angle q_(r). Because the left hip jointangle q_(l) and the right hip joint angle q_(r) vary over time, thecontroller 120 may define the state variable y using, for example, oneof Equation 1 to Equation 3, discussed below.

For example, in some example embodiments, the controller 120 may definethe state variable y using Equation 1:

y ₁(t)=q _(r)(t)−g _(l)(t)  [Equation 1]

In Equation 1, y₁(t) denotes the state variable, q_(r)(t) denotes theright hip joint angle, and q_(l)(t) denotes the left hip joint angle.

In other example embodiments, the controller 120 may define a statevariable in a form of a trigonometric function. The controller 120 mayexpress the left hip joint angle q_(l) by a first trigonometric functionand may express the right hip joint angle q_(r) by a secondtrigonometric function. The controller 120 may define the state variabley based on a difference between the first trigonometric function and thesecond trigonometric function.

The trigonometric function may be a sine function or a cosine function.For example, the controller 120 may define a difference“sin(q_(r))−sin(q_(l))” between the first trigonometric function and thesecond trigonometric function as the state variable y. Also, thecontroller 120 may limit a value of the state variable to a range ofvalues equal to or less than “1.”

For example, the controller 120 may define a state variable using atrigonometric function based on Equation 2 shown below.

y ₂(t)=sin q _(r)(t)−sin q _(l)(t)  [Equation 2]

In Equation 2, y₂( ) denotes the state variable, q_(r)(t) denotes theright hip joint angle, and q_(l)(t) denotes the left hip joint angle.

In still other example embodiments, the controller 120 may define thestate variable y to include a gain A associated with a torque strengthand a delay Δt associated with a torque output time. For example, thecontroller 120 may define the state variable y using Equation 3 shownbelow.

y ₃(t)=A(sin q _(r)(t−Δt)−sin q _(l)(t−Δt))  [Equation 3]

In Equation 3, y₃(t) denotes the state variable, q_(r)(t) denotes theright hip joint angle, q_(l)(t) denotes the left hip joint angle, Adenotes the gain, and Δt denotes the delay.

In some examplc cmbodiments, the dclay may be a value set in advance bythe user 200. For example, the user 200 may set a delay in a unit oftime, for example, seconds (s) or milliseconds (ms), in advance. Thus,the user 200 may hardly feel an assistance delay and may feel a naturalassistance torque matching a motion. The walking assistance apparatus100 may set an assistance torque timing (t−Δt) based on the delay Δt,and may enhance a stability by, for example, finely adjusting themaximum assistance torque generation timing to correspond to a maximumjoint angle.

In other example embodiments, as discussed below, the controller 120 mayautomatically determine the delay Δt based on, for example, a gaitvelocity and/or a gait acceleration of the user 200.

The controller 120 may generate a first torque profile based on thestate variable. The controller 120 may control the driver 130 to outputan assistance torque corresponding to the rust torque profile to a leftleg of the user 200.

Also, the controller 120 may generate a second torque profile bychanging a sign of the first torque profile. The controller 120 maycontrol the driver 130 to output an assistance torque corresponding tothe second torque profile to a right leg of the user 200. The controller120 may also output an assistance torque corresponding to a profile byexchanging the left leg and the right leg.

The controller 120 may differently set magnitudes of assistance torquesthat are to be output to the left leg and the right leg. For example,when the user 200 feels uncomfortable with the left leg and a greaterassistance torque is required for the left leg, the controller 120 mayset a great gain of the first torque profile corresponding to the leftleg. In this example, the driver 130 may output a greater assistancetorque to the left leg rather than the right leg.

Hereinafter, experimental results of a walking assistance methodperformed by the walking assistance apparatus 100 based on the delay Δt(or, alternatively, the delay Δt and gain a) according to exampleembodiments is described with reference to FIGS. 6A to 12.

FIG. 6A illustrates an example for evaluation of the performance of thewalking assistance apparatus 100 of FIG. 1 and FIG. 6B illustratesanother example for evaluation of the performance of the walkingassistance apparatus 100. FIGS. 7A and 7B are a three-dimensional (3D)graph and a two-dimensional (2D) graph illustrating a result obtained byevaluating the performance of the walking assistance apparatus 100,respectively. FIG. 8A illustrates an example of a stability analysis mapassociated with the result of FIGS. 7A and 7B, and FIG. 8B illustratesanother example of a stability analysis map associated with the resultof FIGS. 7A and 7B.

Referring to FIGS. 6A through 8B, the performance of the walkingassistance apparatus 100 may be evaluated using simplified swing legdynamic models. When an equivalent transformation is performed in theexample of FIG. 6A, a result may be obtained as shown in FIG. 6B. InFIGS. 6A and 6B, q_(r) denotes the right hip joint angle, q_(l) denotesthe left hip joint angle, and u denotes an exoskeleton driven torque.

To evaluate the stability of the walking assistance apparatus 100,modeling of a differential equation may be performed with respect toswinging of the left leg and right leg based on the torsion constant K,the moment of inertia I, the mass M, the period T, and the gait angularfrequency w as shown in Equation 4 below.

For example, based on a user who is 165 centimeters tall and weighs 55kilograms, constants used in dynamic modeling may be

${I = {I_{leg} \approx {1\mspace{14mu}{kgm}^{2}}}},{K = {{MgL}_{c} = {30\mspace{14mu}{kgm}^{2}}}},{L_{c} = {0.3483\mspace{14mu} m^{2}}},{M = {8.8550\mspace{14mu}{kg}}},{T_{0} = {\frac{2\pi}{\sqrt{K\text{/}I}} = {1.15\mspace{14mu} s}}},{{{and}\mspace{14mu} w_{0}} = {\sqrt{K\text{/}I} = {5.5\mspace{14mu}{s^{- 1}.}}}}$I{umlaut over (q)} _(r)(t)+B{dot over (q)} _(r)(t)+K sin q _(r)(t)=−u(t)

I{umlaut over (q)} _(l)(t)+B{dot over (q)} _(l)(t)+K sin q _(l)(t)=u(t)

u(t)=Ay(t−Δt)

y(t)=sin q _(r)(t)−sin q _(l)(t)  [Equation 4]

An approximation may be performed and expressed by sin q≈q. When u(t) issubtracted from −u(t) in Equation 4, Equation 5 may be obtained.

ÿ(t)+b{dot over (y)}(t)+ky(t)=−2ay(t−Δt)+τ_(ext)

y(t)=q _(r)(t)−q _(l)(t)  [Equation 5]

In Equation 5, τ_(ext) denotes an external force exerted by aninteraction between the walking assistance apparatus 100 and a user, andmay be expressed by Equation 6 below.

$\begin{matrix}\begin{matrix}{\tau_{ext} = {\tau_{regist} + \tau_{drive}}} \\{= {\left( {{{- k_{ext}}{y(t)}} - {b_{ext}{\overset{.}{y}(t)}}} \right) + {a_{ext}\mspace{14mu}{\cos({wt})}}}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

In Equation 6, τ_(regist) denotes an external force due to resistance,τ_(drive) denotes an external force during walking, w denotes an gaitangular frequency of a user expressed by

$\frac{2\pi}{T_{ext}},$

a denotes an input torque expressed by A/I, k denotes a stiffnesscoefficient of “30” expressed by K/I, and b denotes a dampingcoefficient of “0.01” expressed by B/I.

An approximated characteristic equation may be expressed using a Lambertfunction as shown in Equation 7 below.

$\begin{matrix}{{{\overset{.}{y}(t)} = {{A_{0}{y(t)}} + {A_{1}{y\left( {t - {\Delta\; t}} \right)}}}}{A_{0} = \begin{bmatrix}{{- b} - b_{ext}} & {{- k} - k_{ext}} \\1 & 0\end{bmatrix}}{A_{1} = \begin{bmatrix}0 & {{- 2}a} \\0 & 0\end{bmatrix}}{{sI} = {{\frac{1}{\Delta\; t}{W\left( {A_{1}\Delta\;{te}^{{- A_{0}}\Delta\; t}} \right)}} + A_{0}}}{{eig}\left\{ {{\frac{1}{\Delta\; t}{W\left( {A_{1}\Delta\;{te}^{{- A_{0}}\Delta\; t}} \right)}} + A_{0}} \right\}}{{{Lambert}\mspace{14mu}{function}\mspace{14mu} W},{z = {W\left( {ze}^{z} \right)}}}} & \left\lbrack {{Equation}\mspace{14mu} 7} \right\rbrack\end{matrix}$

In Equation 7, the stability of the walking assistance apparatus 100 maybe determined based on whether a maximum value of a real part of asolution of the characteristic equation is a negative number. Maximumreal values of complex eigenvalues corresponding to the solution of thecharacteristic equation may be expressed by the 3D graph of FIG. 7A andthe 2D graph of FIG. 7B.

Referring to FIGS. 7A and 7B, a first region 610 may indicate anunstable region. The first region 610 may be a non-negative region. Forexample, a plurality of first regions 610 may be present.

When the controller 120 sets the gain a and the delay Δt correspondingto the first region 610, the walking assistance apparatus 100 may bedetermined to be unstable due to a divergence or fluctuation in astability analysis map because a stable focus or a stable limit cycle isnot shown. The stable limit cycle may refer to a regular and repetitivepattern that converges to a periodic motion in association with a gaitcontrol.

In FIGS. 7A and 7B, a second region 620 may include a stable region.When the controller 120 sets the gain a and the delay Δt correspondingto the second region 620, a stability analysis map in a free responseexperiment and a stability analysis map in a forced response experimentof the walking assistance apparatus 100 may be shown in FIGS. 8A and 8B,respectively.

For example, the free response experiment may be a stability experimentconducted when a user stops walking. In the free response experiment,the external force τ_(drive) may be zero during walking.

The forced response experiment may be a stability experiment conductedduring a continuous gait. For example, in the forced responseexperiment, the external force τ_(drive) may be a_(ext) cos (wt).

For example, the second region 620 may include a third region 710,illustrated in FIG. 8A, or a fourth region 720, illustrated in FIG. 8B.When the controller 120 sets the gain a and the delay Δt correspondingto the third region 710 or the fourth region 720, a stable focus may beshown in the free response experiment and a stable limit cycle may beshown in the forced response experiment. In this example, the walkingassistance apparatus 100 may allow a user to maintain regular walking.

FIG. 9A is a graph illustrating a result of an experiment on a change ina gait velocity of a user according to at least one example embodiment,and FIG. 9B illustrates a stability analysis map associated with theresult of FIG. 9A.

Referring to FIGS. 9A and 9B, FIGS. 9A and 9B illustrate a stability ofthe walking assistance apparatus 100 of FIG. 1 measured when the gaitvelocity of the user increases. For example, the user walks at aninterval of 1.5 s and changes the gait velocity to quickly walk at aninterval of 0.5 s after 20 s. In this example, the walking assistanceapparatus 100 may show two stable limit cycles, that is, stable limitcycles 810 and 820 and may stably respond to a sudden change in a motionof the user. Thus, the walking assistance apparatus 100 may have aself-stabilizing characteristic.

FIG. 10 illustrates experimental results when a user repeats walking andstopping according to at least one example embodiment.

Referring to FIG. 10, when a user stops walking, a hip joint range ofmotion (ROM) decreases. For example, the user stops walking at 65 s and75 s. In this example, it is found that the walking assistance apparatus100 immediately responds to a stop of the user, by analyzing a statevariable 910 and an assistance torque 920 of the walking assistanceapparatus 100. Thus, the walking assistance apparatus 100 may exhibit ahigh stability by effectively responding to an intention of the user.

Also, it is found that when the user who is stationary wants to walk,the hip joint ROM increases. For example, the user starts walking at 66s. In this example, it is found that the walking assistance apparatus100 immediately responds to a gait change of the user, by analyzing thestate variable 910 and the assistance torque 920.

FIG. 11 illustrates experimental results when a user who is stationarywants to walk according to at least one example embodiment.

Referring to FIG. 11, when a user who is stationary wants to walk, a hipjoint ROM increases. By analyzing a state variable 1010 and anassistance torque 1020 of the walking assistance apparatus 100, it isfound that the walking assistance apparatus 100 immediately responds toa gait change of the user, as described above.

FIG. 12 illustrates experimental results when a user wants to walkuphill and then downhill according to at least one example embodiment.

Referring to FIG. 12, when a user walks uphill and then downhill, a hipjoint ROM rapidly changes. By analyzing a state variable 1110 and anassistance torque 1120 of the walking assistance apparatus 100, it isfound that the walking assistance apparatus 100 immediately responds toa change in a walking environment of the user.

FIG. 13 is a flowchart illustrating a walking assistance methodperformed by the walking assistance apparatus 100 of FIG. 1 according toat least one example embodiment. FIG. 14 is a flowchart illustrating anoperation of measuring a current gait motion of a user in the walkingassistance method of FIG. 13, FIG. 15 is a flowchart illustrating anexample of an operation of defining a state variable in the walkingassistance method of FIG. 13, and FIG. 16 is a flowchart illustratinganother example of an operation of defining a state variable in thewalking assistance method of FIG. 13.

Referring to FIGS. 13 through 16, in operation 1210, the walkingassistance apparatus 100 may measure the hip joint angular informationas the current gait motion of a user, while for example the user isambulatory. The hip joint angular information may include hip jointangles.

For example, as illustrated in FIG. 14, in operation 1310, the sensor110 measure the left hip joint angle q_(l), and, in operation 1320, thesensor 110 may measure the right hip joint angle q_(r). The sensor 110may transmit the measured hip joint angles to the controller 120.

In some example embodiments, if the user has an abnormal gait type, thegait of the user may be defined by a user inclining their trunk androtating their pelvis rather than their hip joint when walking.Therefore, in some example embodiments, the controller 120 may determinethe hip joint angle by correcting the measured hip joint angles based onan inclination of a trunk of the user and a rotational angular velocityof a pelvis of the user.

Referring back to FIG. 13, in operation 1215, the walking assistanceapparatus 100 may perform low-pass filtering on the hip joint angularinformation. For example, the controller 120 may apply the followingequation to the left hip joint angle q_(l) the right hip joint angleq_(r).

q[i]=(1−α)q[i−1]+αq _(raw)[i], (0<α<1)

Where q_(raw)└i┘ is the hip joint angle measured by the sensor, α is avariable between zero and one, and q[i] is the low-pass filtered hipjoint angular information.

In operation 1220, the walking assistance apparatus 100 may define astate variable y based on the current gait motion (e.g., q_(l) andq_(r)). Such that the walking assistance apparatus 100 may utilize thecurrent gait motion as feedback when defining the state variable.

For example, in some example embodiments, as illustrated in FIG. 15, inoperation 1410, the controller 120 may receive the current gait motion(e.g., the hip joint angular information) as a feedback, define thestate variable y based on a difference between the left hip joint angleand the right hip joint angle included in the hip joint angularinformation. For example, the controller 120 may utilize Equation 1,which represents the hip joint motion in joint space, to define thestate variable y.

In other example embodiments, as illustrated in FIG. 16, the controller120 may define the state variable y using a trigonometric function, suchas Equation 2, which represents the hip joint motion in ground projectedtask space. In operation 1510, the controller 120 may express the lefthip joint angle q_(l) by a first trigonometric function. In operation1520, the controller 120 may express the right hip joint angle q_(r) bya second trigonometric function. In operation 1530, the controller 120may define the state variable based on a difference between the firsttrigonometric function and the second trigonometric function.

Referring back to FIG. 13, in operation 1230, the walking assistanceapparatus 100 may set the delay Δt for the state variable y. The delayΔt may be a feedback element.

For example, in some example embodiments, the controller 120 may receivethe delay Δt, which is set in advance by a user. For example, the usermay set a delay in a unit of time, for example, seconds (s) ormilliseconds (ms), in advance.

In other example embodiments, the controller 120 may automaticallydetermine the delay Δt adaptively.

For example, the controller 120 may determine the delay Δt based on agait velocity of the user 200. The controller 120 may set a relativelyshort delay Δt in response to the gait velocity being greater than afirst reference value, and may set a relative long delay Δt in responseto the gait velocity being less than the first reference value. Thecontroller 120 may measure the gait velocity based on the current gaitmotion received from the sensor 110.

In some other example embodiments, the controller 120 may determine thedelay Δt based on the gait acceleration of the user 200. The controller120 may set a relatively short delay Δt in response to the gaitacceleration being greater than a second reference value, and may set arelatively long delay Δt in response to the gait acceleration being lessthan the second reference value.

In operation 1240, the walking assistance apparatus 100 may generate atorque profile based on the state variable y. For example, the walkingassistance apparatus 100 may generate a first torque profilecorresponding to a left leg. The walking assistance apparatus 100 maygenerate a second torque profile by changing a sign of the first torqueprofile. The walking assistance apparatus 100 may output an assistancetorque to the left leg based on the first torque profile, and may outputan assistance torque to a right leg based on the second torque profile.

In some example embodiments, the torque profile may include torqueparameters Torque Start l_(start), Torque Period d_(ascd), Torque Peakl_(peak), Torque Quantity τ_(peak), Torque Peak Duration d_(peak), andTorque Decrease Duration d_(dsed).

In some example embodiments, the walking assistance apparatus 100 mayadjust the torque profile/output torque based on the weight of the user.For example, the controller 120 may receive data from either a userinput or from sensors indicating the weight of the users, and mayincrease or decrease the torque profile based on whether the weight ofthe user is above or below a threshold.

In operation 1245, the walking assistance apparatus 100 may adjust thegain A of the first (left) torque profile and a gain of the second(Right) torque profiles by adjusting the state variable.

For example, the controller 120 may utilize Equation 3 to determine thestate variable y, and set the gain A applied to the state variable Abased on, for example, user input.

For example, the controller 120 may display, via the display 140, a userinterface (UI) configured to control the gain A. For example, the user200 may control, using the UI displayed on the display 140, the gain Aassociated with a strength of an assistance torque. The controller 120may utilize the gain A input by the user when calculating the statevariable y.

Further still, in other example embodiments, during rehabilitation, asecond user (e.g., a physical therapist), may set the gain A, forexample, via a remote controller, as a negative value to graduallyreduce the amount of assistance force provided over time.

In operation 1250, the walking assistance apparatus 100 may generate andapply the assistance torque based on the torque profile (or,alternatively the gain adjusted torque profile).

For example, the controller 120 may instruct the driver 130 to generatethe assistance torque and apply the same to the body of the user toassist the user with walking.

Since the walking assistance apparatus 100 utilizes the delay Δt forfeeding back the state variable y rather than a scheme of applying apredefined torque pattern based on a gait phase, the walking assistanceapparatus 100 may match timing corresponding to swing at the maximumvelocity (in the vicinity of a point in time at which left/right hipjoints cross) with the timing of applying the maximum assistance torque.Further, due to the time delay Δt, the walking assistance apparatus 100may quickly and reliably cope with sudden stopping or changes in a gaitspeeds or environmental changes (e.g., stairs and/or ramps), andabnormal gait patterns of a user (e.g., a gait pattern of user with astroke, CMT or Parkinsons) without any additional sensors orcomputational processing. Thus, the user may hardly feel an assistancedelay and may feel a natural assistance torque matching a motion.

In some example embodiments, prior to generating the assistance torque,the walking assistance apparatus 100 may select an abnormal gait type,and, in operation 1250, the controller may generate the assistancetorque based on the torque profile and the selected abnormal gait type.

In some example embodiments, the abnormal gait type may be input by theuser via, for example, a remote control.

In other example embodiments, rather than selecting an abnormal gaittype. the walking assistance apparatus 100 may automatically estimatethe abnormal gait type. For example, the controller 120 may utilizeelectromyogram (EMG) signals from muscles of the user and motion datafrom joints of the user to estimate the abnormal gait type.

Hereinafter, examples of systems implementing the walking assistanceapparatus 100 will be described.

FIG. 17 is a block diagram illustrating a walking assistance system 1600according to at least one example embodiment.

Referring to FIG. 17, the walking assistance system 1600 may include thewalking assistance apparatus 100 and a parameter generation apparatus300.

The parameter generation apparatus 300 may analyze an existing gaitpattern of a user, and may generate and store the torque parameters. Thewalking assistance apparatus 100 may receive the torque parameters fromthe parameter generation apparatus 300, and may generate the assistancetorque based on the torque parameters.

The walking assistance apparatus 100 may receive the torque parametersusing a feedforward scheme, and may receive a current gait motion usinga feedback scheme. The walking assistance apparatus 100 may define thestate variables based on the torque parameters and the current gaitmotion, may generate the torque profile based on the state variables,and may output the assistance torque based on the torque profile.

For example, a user may select a gait type of the user from a pluralityof abnormal gait types using the display 140. The controller 120 mayreceive, in advance, the abnormal gait type of the user, and may outputthe assistance torque corresponding to the abnormal gait type.

FIG. 18 is a graph illustrating an example of using the walkingassistance apparatus 100 as a phase estimator according to at least oneexample embodiment.

In FIG. 18, the walking assistance apparatus 100 may be used as a phaseestimator. FIG. 18 illustrates a result obtained by estimating a gaitphase 1720 of a user based on a state variable 1710 defined by thewalking assistance apparatus 100. For example, the walking assistanceapparatus 100 may estimate the gait phase 1720 using Equation 8 shownbelow.

$\begin{matrix}{{{phase} = {\frac{1}{2\pi}{atan}\; 2\left( {{{cy}\left( {t - {\Delta\; t}} \right)},{\overset{.}{y}\left( {t - {\Delta\; t}} \right)}} \right)}}{{y(t)} = {{\sin\mspace{14mu}{q_{r}(t)}} - {\sin\mspace{14mu}{q_{l}(t)}}}}} & \left\lbrack {{Equation}\mspace{14mu} 8} \right\rbrack\end{matrix}$

In Equation 8, Δt denotes the delay, and c denotes a scaling factor usedto perform scaling.

While Equation 8 is shown utilizing Equation 2 to define the statevariable y, example embodiments are not limited thereto. For example, inother example embodiments, the phase estimator may utilize Equation 1 todefine the state variable y when determining the phase.

Referring to FIG. 19, the walking assistance system 1800 may include thewalking assistance apparatus 100 and a remote controller 1810.

The remote controller 1810 may control an overall operation of thewalking assistance apparatus 100 in response to a user input. Forexample, the remote controller 1810 may initiate or stop an operation ofthe walking assistance apparatus 100. Also, the remote controller 1810may control an output of a torque profile to control the walkingassistance apparatus 100 to assist a gait of a user.

The remote controller 1810 may include a display 1830. The display 1830may be implemented as, for example, a touch screen, an LCD, a TFT-LCD,an LED display, an OLED display, an AMOLED display or a flexibledisplay.

The remote controller 1810 may provide a user with a UI and/or a menucorresponding to a function for operating the walking assistanceapparatus 100, using the display 1830. For example, the remotecontroller 1810 may be a device for a manual operation of a user. Forexample, a user may select a start, stop or end of gait assistance.Also, the user may select an abnormal gait type and may receive a gaitassistance based on the selection. The remote controller 1810 mayreceive an input from a user through the display 1830.

The display 1830 may include a touch screen that provides a UI or amenu. The display 1830 may display an operating state of the walkingassistance apparatus 100 to the user under a control of the remotecontroller 1810. The operating state of the walking assistance apparatus100 displayed by the display 1830 may include, for example, an outputtorque, a current gait motion of a user or an abnormal gait typeselected by the user.

FIG. 20 is a block diagram illustrating a walking assistance system 1900according to at least one example embodiment.

Referring to FIG. 20, the walking assistance system 1900 may include thewalking assistance apparatus 100, a remote controller 1910, and anelectronic device 1930.

A configuration and operation of the remote controller 1910 may besubstantially the same as a configuration and operation of the remotecontroller 1810 of FIG. 19.

The electronic device 1930 may communicate with the walking assistanceapparatus 100 and/or the remote controller 1910.

The electronic device 1930 may be implemented as, for example, aportable electronic device including a display 1950.

The portable electronic device may be implemented as, for example, alaptop computer, a mobile phone, a smartphone, a tablet personalcomputer (PC), a mobile Internet device (MID), a personal digitalassistant (PDA), an enterprise digital assistant (EDA), a digital stillcamera, a digital video camera, a portable multimedia player (PMP), apersonal navigation device or portable navigation device (PND), ahandheld game console, an e-book, or a smart device. The smart devicemay be implemented as, for example, a smart watch or a smart band.

The electronic device 1930 may include a biosensor that senses abiosignal of a user, and may transmit the sensed biosignal to thewalking assistance apparatus 100 and/or the remote controller 1910.

In other example embodiments, the walking assistance apparatus 100 maybe included in a tremor control system. For example, the walkingassistance apparatus 100 may be used as a handheld device to compensatefor a hand tremor. The walking assistance apparatus 100 may beapplicable to various handheld devices capable of interacting with usersas well as a wearable exoskeleton robot.

In other example embodiments, the walking assistance apparatus 100 maybe included in a vibration reduction system. For example, the walkingassistance apparatus 100 may be utilized for a vibration reductioncontrol of a surgical robot tool, a master device and/or a robotic slavedevice. The walking assistance apparatus 100 may employ a small numberof sensors, and accordingly it is possible to reduce maintenance costsfor calibration of the sensors by reducing a possibility of amalfunction and error of the sensors in various situations by a contactwith a user. Also, it is possible to provide a degree of freedom in adesign and usability by innovatively reducing a weight and volume of thewalking assistance apparatus 100.

FIG. 21 illustrates a flowchart illustrating method of operating awalking assistance system for tremor control according to at least oneexample embodiment.

Referring to FIG. 21, in operation 2010, the controller 120 may measurea user's current hand motion. In operation 2020, the controller 120 maydefine the state variable y. In operation 2030, the controller 120 mayset the delay for the state variable. In operation 2040, the controller120 may generate a torque profile based on the state variable. Inoperation 2050, the controller 120 may instruct a driver to move thesurgical robot tool such that surgical robot tool docs not respond totremors present in the measured hand motion.

The units and/or modules described herein may be implemented usinghardware components, software components, or a combination thereof. Forexample, the hardware components may include microphones, amplifiers,band-pass filters, audio to digital convertors, and processing devices.A processing device may be implemented using one or more hardware deviceconfigured to carry out and/or execute program code by performingarithmetical, logical, and input/output operations. The processingdevice(s) may include a processor, a controller and an arithmetic logicunit, a digital signal processor, a microcomputer, a field programmablearray, a programmable logic unit, a microprocessor or any other devicecapable of responding to and executing instructions in a defined manner.The processing device may run an operating system (OS) and one or moresoftware applications that run on the OS. The processing device also mayaccess, store, manipulate, process, and create data in response toexecution of the software. For purpose of simplicity, the description ofa processing device is used as singular; however, one skilled in the artwill appreciated that a processing device may include multipleprocessing elements and multiple types of processing elements. Forexample, a processing device may include multiple processors or aprocessor and a controller. In addition, different processingconfigurations are possible, such a parallel processors.

The software may include a computer program, a piece of code, aninstruction, or some combination thereof, to independently orcollectively instruct and/or configure the processing device to operateas desired, thereby transforming the processing device into a specialpurpose processor. Software and data may be embodied permanently ortemporarily in any type of machine, component, physical or virtualequipment, computer storage medium or device, or in a propagated signalwave capable of providing instructions or data to or being interpretedby the processing device. The software also may be distributed overnetwork coupled computer systems so that the software is stored andexecuted in a distributed fashion. The software and data may be storedby one or more non-transitory computer readable recording mediums.

The methods according to the above-described example embodiments may berecorded in non-transitory computer-readable media including programinstructions to implement various operations of the above-describedexample embodiments. The media may also include, alone or in combinationwith the program instructions, data files, data structures, and thelike. The program instructions recorded on the media may be thosespecially designed and constructed for the purposes of exampleembodiments, or they may be of the kind well-known and available tothose having skill in the computer software arts. Examples ofnon-transitory computer-readable media include magnetic media such ashard disks, floppy disks, and magnetic tape; optical media such asCD-ROM discs, DVDs, and/or Blue-ray discs; magneto-optical media such asoptical discs; and hardware devices that are specially configured tostore and perform program instructions, such as read-only memory (ROM),random access memory (RAM), flash memory (e.g., USB flash drives, memorycards, memory sticks, etc.), and the like. Examples of programinstructions include both machine code, such as produced by a compiler,and files containing higher level code that may be executed by thecomputer using an interpreter. The above-described devices may beconfigured to act as one or more software modules in order to performthe operations of the above-described example embodiments, or viceversa.

A number of example embodiments have been described above. Nevertheless,it should be understood that various modifications may be made to theseexample embodiments. For example, suitable results may be achieved ifthe described techniques are performed in a different order and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents. Accordingly, other implementations arewithin the scope of the following claims.

What is claimed is:
 1. A walking assistance method comprising: measuringa current gait motion of a user; defining a state variable based on thecurrent gait motion; setting a delay associated with the state variable;and generating a torque profile based on the state variable and thedelay such that the delay is a feedback element defining an output timeof torque corresponding to the torque profile.
 2. The walking assistancemethod of claim 1, further comprising: filtering the current gaitmotion.
 3. The walking assistance method of claim 2, wherein thefiltering of the current gait motion comprises: performing low-passfiltering of the current gait motion using a low-pass filter (LPF). 4.The walking assistance method of claim 1, wherein the measuring of thecurrent gait motion comprises: measuring at least one hip joint angle ofthe user.
 5. The walking assistance method of claim 4, wherein themeasuring of the at least one hip joint angle comprises: measuring aleft hip joint angle of the user; and measuring a right hip joint angleof the user.
 6. The walking assistance method of claim 5, wherein thedefining of the state variable comprises: defining the state variablebased on a difference between the left hip joint angle and the right hipjoint angle.
 7. The walking assistance method of claim 1, wherein thedefining of the state variable defines the state variable such that thestate variable is expressed in a form of a trigonometric function. 8.The walking assistance method of claim 7, wherein the defining of thestate variable comprises: expressing a left hip joint angle of the userbased on a first trigonometric function; expressing a right hip jointangle of the user based on a second trigonometric function; and definingthe state variable based on a difference between the first trigonometricfunction and the second trigonometric function.
 9. The walkingassistance method of claim 1, wherein the state variable includes thedelay and a gain associated with the torque.
 10. The walking assistancemethod of claim 9, wherein the defining of the state variable comprises:determining the delay based on a gait velocity of the user.
 11. Awalking assistance apparatus comprising: a sensor configured to measurea current gait motion of a user; and a controller configured to, definea state variable based on the current gait motion, set a delay for thestate variable, and generate a torque profile based on the statevariable and the delay such that the delay is a feedback elementdefining an output timing of a torque corresponding to the torqueprofile.
 12. The walking assistance apparatus of claim 11, furthercomprising: a filter configured to filter the current gait motion. 13.The walking assistance apparatus of claim 12, wherein the filtercomprises: a low-pass filter (LPF) configured to perform low-passfiltering on the current gait motion.
 14. The walking assistanceapparatus of claim 11, wherein the sensor is configured to measure a hipjoint angle of the user as the current gait motion.
 15. The walkingassistance apparatus of claim 14, wherein the sensor is configured to,measure a left hip joint angle of the user, and measure a right hipjoint angle of the user.
 16. The walking assistance apparatus of claim15, wherein the controller is configured to define the state variablebased on a difference between the left hip joint angle and the right hipjoint angle.
 17. The walking assistance apparatus of claim 11, whereinthe controller is configured to define the state variable such that thestate variable is expressed in a form of a trigonometric function. 18.The walking assistance apparatus of claim 17, wherein the controller isconfigured to define the state variable by, expressing a left hip jointangle of the user based on a first trigonometric function, expressing aright hip joint angle of the user based on a second trigonometricfunction, and defining the state variable based on a difference betweenthe first trigonometric function and the second trigonometric function.19. The walking assistance apparatus of claim 11, wherein the statevariable includes the delay and a gain associated with the torque. 20.The walking assistance apparatus of claim 19, wherein the controller isconfigured to determine the delay based on a gait velocity of the user.